The invention concerns a method of operating a wind park and also a wind park as such.
Wind power installations were initially always set up as singular units and it is only in recent years that wind power installations have frequently been installed in wind parks, this being due also to administrative and building regulations. In that respect a wind park, in its smallest entity, is an arrangement of at least two wind power installations but frequently markedly more. By way of example mention may be made of the wind park at Holtriem (East Frisia in Germany), where more than 50 wind power installations are set up in an array. It is to be expected that the number and also the installed power output of the wind power installations will also rise greatly in future years. In most cases the wind potential is at its greatest in regions of the power supply networks with a low short-circuit capacity and a low level of population density. It is precisely there that the technical connection limits are rapidly attained by the wind power installations, with the consequence that no further wind power installations can then be set up at such locations.
A conventional wind park which is connected for example to a 50 MW substation can therefore have at a maximum only 50 MW total power output, that is to say for example 50 wind power installations each involving a rated power output of 1 MW.
Bearing in mind the fact that the wind power installations are not constantly operated at the rated level and thus the entire wind park also does not continuously reach its maximum power output (rated power output), it can be established that the wind park is not put to optimum use if the rated power output of the wind park corresponds to the maximum possible total power output which is to be fed in.
The invention accordingly proposes a solution in which the wind park is equipped with a total power output which is higher than the maximum possible network feed-in power output. When applied to the above-indicated example, the power output can be raised to a value of over 50 MW, for example 53 MW. As soon as the wind speeds are sufficiently high to produce a limit power output of 50 MW, the wind park regulation in accordance with the invention comes into operation and regulates down individual ones of or all installations when the total maximum power output is exceeded, in such a way that same is always observed. This means that, at wind speed above nominal or rated wind (wind speed at which a wind power installation reaches its rated power output), at least one or all installations is or are operated with a (slightly) throttled power output (for example with a power output of 940 kW instead of 1 MW).
The advantages of the invention are apparent. Considered overall the network components of the feed network (network components are for example the transformer and the lines) are utilized or loaded in the optimum fashion (utilization up to the thermal limit is also a possibility). This means that existing wind park areas can be better utilized, by virtue of setting up a maximum possible number of wind power installations. That number is then no longer (so severely) limited by the existing network capacity.
For the purposes of control/regulation of a wind power installation, it is desirable if it has a data input, by means of/by way of which the electric power output can be adjusted in a range of between 0 and 100% (with respect to the rated power output). If for example a reference value of 350 kW is applied to that data input, the maximum power output of that wind power installation will not exceed the reference value of 350 kW. Any value between 0 and the rated power output (for example from 0 to 1 MW) is possible as the reference value.
That data input can be used directly for power output limitation purposes.
It is however also possible by means of a regulator to regulate the generator output in dependence on the network voltage (in the wind park network or in the feed network).
A further important function is discussed hereinafter with reference to wind park regulation. It will be assumed by way of example that a wind park comprises 10 wind power installations which each have a rated power output of 600 kW. By virtue of the capacitances of the network components (line capacitances) or the limited capacitances in the substation it will further be assumed that the maximum power output to be delivered (limit power output) is limited to 5200 kW.
There is now the possible option of limiting all wind power installations to a maximum power output of 520 kW by means of the reference value (data input). That satisfies the requirement for limiting the power output to be delivered.
Another possible option involves not exceeding the maximum power output, as the sum of all installation, but at the same time generating a maximum amount of power (kW-hours (work)).
In that respect, it should be known that, at low to moderate wind speeds, within the wind park, it frequently comes about that the wind power installations at the favorable (good) locations (these are the locations at which the wind impinges first within the wind park) receive a great deal of wind. If now all wind power installations are simultaneously regulated down to their throttled value (for example all to 520 kW), that generated power output is admittedly attained by some wind power installations which are disposed at good locations, but some other wind power installations which stand in the xe2x80x9cwind shadowxe2x80x9d of the well-located wind power installations (being in the second and third rows) receive less wind and as a result operate for example only with a power output of 460 kW and do not reach the value of the maximum throttled power output at 520 kW. The total power output generated in the wind park is accordingly substantially below the permitted limit power output of 5200 kW.
In this case the wind park power output regulation procedure according to the invention regulates the individual installations in such a way that the maximum possible energy yield occurs. This means in specific terms that for example the installations in the first row (that is to say at good locations) are regulated to a higher power output, for example to the rated power output (that is to say no throttling action). This means that the overall electrical power output in the wind park rises. The park regulation arrangement however regulates each individual installation in such a way that the maximum permitted electrical connection power output is not exceeded while at the same time the work produced (kWh) reaches a maximum value.
The wind park management according to the invention can be easily adapted to the respective situations which arise. Thus it is very easily possible for example to implement different throttling of the power output of individual installations if an individual installation or a plurality of installations of a wind park are (have to be) taken off the network, if either for maintenance reasons or for other reasons and an individual installation or a plurality of installations have to be temporarily shut down.
For control/regulation of the wind park or the individual installations, it is possible to use a data/control processing apparatus which is connected to the data inputs of the installations and which, from the wind speeds which are ascertained (in respect of each installation), ascertains the respectively most advantageous power output throttling value for an individual installation or the entire wind park respectively.